Hi. I see you haven't had any replies yet. Is this for the summer or for parallel work in term time? What help does she need? (As in why do you think that whatever the school is doing, that you are paying for, won't be sufficient?)

I'm a secondary school English teacher and tbf I'd just encourage her to read widely - novels, non-fiction (biographies, autobiographies, history books etc of anything she's interested in) magazines, blogs, newspapers, articles online etc. Anything she enjoys. If you want to do 'exercises' perhaps a reading log of some kind with some summaries about the key information/plot points are but don't make it a chore.

As another poster has said, encourage her to read widely. Non fiction is often a weaker/under-developed area in my experience. If she is shaky on elements of writing skills then CGP do some workbooks which are worth doing as a refresher.